The effect of repeated cryopreservation and thawing using cryotip on the clinical outcomes of embryos

• Main Authors: Yamato Mizobe, Yukari Kuwatsuru, Yuko Kuroki, Yumiko Fukumoto, Mari Tokudome, Harue Moewaki, Mia Watanabe, Tatsunori Tabira, Tokiko Iwakawa, Kazuhiro Takeuchi
• Format: Article
• Language: English
• Published: Wiley 2021-04-01
• Series: Reproductive Medicine and Biology
• Subjects: birth weight; blastocyst; closed carriers; CryoTip; re‐cryopreserved
• Online Access: https://doi.org/10.1002/rmb2.12365

Abstract Purpose To compare the clinical outcomes of embryo transfers that were cryopreserved and thawed two or three times with those cryopreserved and thawed once by CryoTip. Methods Data for 388 single cryopreserved‐thawed blastocyst transfer cycles, performed from April 2012 to March 2014, were assessed. The blastocysts were classified into three groups: blastocysts (A) cryopreserved once, (B) cryopreserved twice, and (C) cryopreserved three times. Results The pregnancy rate was 43.8% (134/306) in group A and 46.3% (38/82) in group B, while the miscarriage rate was 29.1% (39/134) in group A and 23.7% (9/38) in group B. The rate of improvement/maintenance of blastocyst grade was 84.0% (257/306) in group A and 80.5% (66/82) in group B. The pregnancy and miscarriage rates of the blastocysts that showed improvement/maintenance in the grade were 45.9% (118/257) and 29.7% (35/118) in group A and 48.5% (32/66) and 21.9% (7/32) in group B, respectively. The pregnancy rate was 33.3% (2/6), while the miscarriage rate was 0.0% (0/2) in group C. Conclusions Pregnancy rates achieved with re‐cryopreserved and rethawed blastocyst transfer were comparable to those achieved with single cryopreserved‐thawed blastocyst transfer.